1. Field of the Invention
The present invention relates to a fatty acid ester-microencapsulated xcex2-D-galactosidase and milk containing the same. More particularly, the present invention relates to easy digestion of milk by adding xcex2-D-galactosidase microencapsulated with fatty acid ester.
2. Description of the Prior Art
In milk, lactose is contained at an amount of about 4.8-5.2%. After ingestion of milk, lactose is hydrolyzed to galactose and glucose, which are both well absorbed in the small intestine, by xcex2-D-galactosidase an enzyme produced in the small intestine. Nearly all infants and children are able to digest lactose. In contrast, a majority of adults in certain population groups are deficient in xcex2-D-galactosidase, which makes them intolerant of milk. In a xcex2-D-galactosidase-deficient adult, lactose accumulates in the lumen of the small intestine after ingestion of milk because there is no mechanism for the uptake of this disaccharide. The large osmotic effect of the unabsorbed lactose leads to an influx of fluid into the small intestine. At the caecum, the unabsorbed lactose is fermented to organic acids by the enteric bacteria. Hence, the clinical symptoms of lactose intolerance are abdominal distention, nausea, cramping, pain, and watery diarrhea. xcex2-D-galactosidase deficiency, whose reason is not clearly revealed, appears to be inherited and postnatal. The prevalence of xcex2-D-galactosidase deficiency in human populations varies greatly. For example, 3% of Danes are deficient in xcex2-D-galactosidase, compared with 97% of Thais and 84% of Koreans. About two-thirds of the population the world over are reported to be problematic in digesting milk. The adults deficient in xcex2-D-galactosidase are reluctant to take milk. It is nutritiously beneficial, particularly, in an aspect of calcium metabolism, for older people to ingest milk, but most of them do not ingest the recommended daily amount (500 ml/day).
In order to help the lactose of milk ve digested and well absorbed in the body, xcex2-D-galactosidase would be added to the milk. However, the glucose and galactose resulting from the hydrolysis action of the enzyme makes the milk too sweet for the consumers to drink. Hence, it is necessary that the xcex2-D-galactosidase added be designed to hydrolyze the lactose only after ingestion of milk.
Conventionally, the lactose content of milk is lowered by adding xcex23-D-galactosidase or immobilized xcex2-D-galactosidase to milk during milk processing to hydrolyze the disaccharide to the monosaccharides (Am. J. Gastroenterol. 83, 1145 (1988); Am. J. Clin. Nutr. 32, 1989 91979); Am. J. Clin. Nutr. 41, 222 (1985); U.S. Pat. No. 1,350,003). The lactose-hydrolyzed milk produced by these techniques, however, is much higher in sweetness than general milk, so it is not so suitable to drink.
In 1980s, to avoid this problem, milk was sold together with a pack of powdered xcex2-D-galactosidase in U.S.A. Men or women who are troubled in digesting milk could take the powdered enzyme upon ingestion of milk. Preventive as it is of increasing the sweetness of milk, this effort is very cumbersome to the consumers.
In 1990s, a further advanced milk product was developed. The milk was free of lactose because it was removed through ultra filtration (UF). However, removal of lactose is accompanied by a great loss of an important nutrient as well as of milk""s characteristic flavor. Also, this technique has a significant disadvantage of decreasing the product yield by 5%. In addition, the UF apparatus is very expensive and continuously needs supplies, such as filters, cleansing agent, etc, giving rise to a significant increase of cost.
An advanced technique is disclosed in Korean Pat. Nos. 088464 and 088465. According to the patents, butter is melted at 40xc2x0 C. for 6 hours, dispersed at 50xc2x0 C. by use of the supernatant fat, emulsified with the aid of an emulsifying agent, and sprayed under a high pressure into low-pat milk (pat content 1% or less) at 5-10xc2x0 C. to coat lactose. As a result, capsules 5-20 xcexcm in diameter are produced at a yield of about 85%. For its preparation, the emulsion requires a long time and a high temperature (50xc2x0 C.), which may be factors to cause degradation in the production yield and in the quality of the fat, respectively. Further, since fat is used as the coating agent, low-fat milk is needed, requiring a cream separation process. In addition, the emulsifying agent used generally smells bad, giving unpleasant flavor to the milk. Furthermore, the capsules are too large in diameter and so rise to the surface of milk after storage for 2-5 hours.
Therefore, it is an object of the present invention to overcome the above problems encountered in prior arts and to provide a xcex2-D-galactosidase which does not exert its hydrolysis function in milk but hydrolyze lactose in the human body.
It is another object of the present invention to provide milk which does not change in sweetness with storage and is digestible to the xcex2-D-galactosidase-deficient people.
It is a further object of the present invention to provide milk which maintains its characteristic taste without off-flavor.
In accordance with an aspect of the present invention, there is provided a xcex2-D-galactosidase encapsulated with fatty acid ester.
In accordance with another aspect of the present invention, there is provided milk which contains the xcex2-D-galactosidase encapsulated with fatty acid ester.
In the present invention, medium chain triglyceride (MCT), decaglycerin monostearate (PGMS) or a combination thereof is used as a coating agent to encapsulate xcex2-D-galactosidase. It is preferable that the production yield of the micro-encapsulated xcex2-D-galactosidase is measured to obtain an optimal condition for encapsulation. The influence of the microencapsulated xcex2-D-galactosidase on the taste and odor of the milk is investigated through functional tests and its medicinal effect is examined through a clinical demonstration in which milk-intolerant persons drink the milk containing the microencapsulated xcex2-D-galactosidase and their clinical symptoms are monitored.
Fatty acid ester, used as food additive, is non-toxic, tasteless, and odorless. In accordance with the present invention, fatty acid ester is used as a coating agent to encapsulate lactose. Use of fatty acid ester is very advantageous in many aspects. First, the time and temperature needed in preparing the emulsion can be significantly reduced. In addition, it is unnecessary to subject milk to cream separation since no fat is added. No additional emulsifying agent is needed. Further, capsules can be produced at a yield of at least 95% with a diameter of 2-3 xcexcm. These microcapsules are uniformly dispersed in milk and do not change for the term of validity of milk (about 10 days). The milk containing the encapsulated lactose gives no off-flavor and is similar in sweetness and general flavor to typical milk.
MCT and PGMS are used as coating agents in the present invention. xcex2-D-galactosidase is mixed with MCT and/or PGMS and the mixture is sprayed and centrifuged to confine the xcex2-D-glactosidase to microcapsules. The production yield of the micro-encapsulated xcex2-D-galactosidase is calculated by measuring the activity of the xcex2-D-galactosidase which is not encapsulated in the spray.
The microencapsulated xcex2-D-galactosidase is added to milk which is, then, subjected to functional tests for flavor and off-flavor and to clinical demonstration to milk-intolerant patients.
A better understanding of the present invention may be obtained through the following examples which are set forth to illustrate, but are not to be construed as the limit of the present invention.